The present invention relates to a conveyor system of dust containers used in buildings wherein the dust container takes the form of a capsule packed with dust and made of a pliable synthetic resin sheet.
Dust discarded from homes in a tall apartment house or an office building has been collected by packing the dust in vinyl bags, and the bags are dropped down through a vertical dust chute having a diameter of about 500 mm.
However, since the height of the apartment house becomes higher year by year, the faster falling speed of the dust bags are, such that the dust bags are broken by colliding against the wall of the dust chute during falling or against the ground surface. Once broken, inside walls of the vertical dust chute would be contaminated, and then arise hygienic problems, such as bad smell, growth of noxious insects and etc.
To prevent these problems, there have been proposed various measures. According to one solution, the dust is sealed in a predetermined volume, and the gap between the outer diameter of the capsule and the inner diameter of the vertical dust chute is made small. Furthermore the weight of the capsule and the pressure in the dust chute are controlled to balance the gravity and the air pressure resistance against the falling capsule. According to another solution, a rising air stream is created in the vertical dust chute and the flow speed of the rising air speed is controlled to correspond to the falling speed of the capsule. The air speed is set at a point above the rising air stream so as to make constant the falling speed of the capsule whereby the capsule can reach the ground without any shock. According to the other solution, a deceleration pipe having a smaller diameter than the inner diameter of the dust chute is connected just above the lower end of the dust chute. (Reference is made to Japanese Laid Open Patent Specification Nos. 286/1985, 25280/1985 and 160904/1985)
According to the above prior arts, it is necessary to use a dust capsule having a definite shape. A large plastic vessel has troubles for recovery and washing. In a throwable vessel (capsule) such as a small paper bag which can be readily moved or carried by housewives, there is a trouble of transferring the dust from one to other capsule. 700-800 capsules are used in one house a year, so that the cost of the capsules becomes a huge amount. For this reason, using such capsules is limited. Where the diameter of the dust chute increases, the weight of the dust capsule also increases so that it is necessary to increase the pressure of the rising air stream necessary to prevent rapid dropping of the capsule. To this end, it is necessary to minimize as far as possible the gap between the inner surface of the chute and the outer surface of the capsule. For the purpose of making the storage space small, solid capsules are generally take the form of a frustoconical shape for easily piling up. As a consequence, it is impossible to gradually decrease the gap area, at a constant rate, in the longitudinal direction of the capsule. For causing the capsule to drop at a definite speed by balancing with each other the air resistance and the capsule weight it is necessary to make the gap small between the upper portion of the capsule where its diameter is large and the inner surface of the dust chute. However, it is difficult to predetermine correct dimension of the clearance.
Where the gap between the capsule and the vertical chute is decreased, the capsule often contacts against the inner wall of the dust chute and is broken.
In the solution described above, wherein a speed decreasing pipe having a small diameter is installed near the lower end of the dust chute for softly landing the capsule, the falling speed would increase at a portion of the chute of a large diameter, there is a tendency that the capsule would be damaged when it enters into the speed decreasing pipe causing splashing of the dust and spoiling the inside of the dust chute.
In the other solution wherein air is blown up by a blower installed at the lower end of the dust chute for decreasing the falling speed of the capsule, not only the cost of installation increases but also maintenance of the equipment is trouble.